The present invention relates to a new and improved device for transferring a weft or filling thread from the weft thread beat-up position to the path of movement of a weft thread picker or insertion element of a shuttleless loom, particularly a gripper loom.
More specifically, the invention is concerned with a transfer device having a transfer mechanism controllable in synchronism with the movement of the loom sley or batten. The transfer mechanism comprises a transfer lever which executes an oscillatory movement and has a thread clamp at its free end. A fixed clamping surface on the transfer lever cooperates with a movable clamping surface.
In shuttleless power looms, particularly gripper looms, it is necessary according to conventional techniques to fixedly clamp the end of the preceding weft thread in the weft thread beaten-up position and before it is cut-off, in order to then bring the newly formed leading end of the next weft thread into the path of movement of the weft thread gripper.
From Swiss Pat. No. 533,190 one such type of transfer device is already known in which the movable clamping surface is formed by an element which has a clamping jaw and which is displaceable on the transfer lever, which in this case is rotatable, and the entire arrangement being under the influence of a helical spring.
However, with this prior art arrangement, there is achieved a clamping effect which is neiher sufficiently controllable nor secure. The latter is so because there prevail considerable centrifugal forces in the region of the clamping jaw and because of the fact that the rigidity of the clamping member makes it sensitive to vibrations. Moreover, the functional reliability of this arrangement can be quickly lost by the accumulation of fluff at the transfer device. Consequently, this increases the danger that the insufficiently clamped thread will be inserted insufficiently deeply into the clamp or nipper of the weft thread gripper.
In Austrian Pat. No. 258,228 a thread clamp is proposed wherein its movable clamping surface is formed by a suitably shaped leaf spring, but the leaf spring here acts with its longitudinal axis in the picking direction of the thread, which leads to relatively indeterminable clamping conditions. Moreover, the structure is voluminous, resulting in long and thus inexact actuating paths. Likewise, there is the danger of the clamping region being obstructed or clogged by fluff.